The present invention relates to a system for recognizing different types of sheets particularly different denominations of bank notes.
Current bank note denomination recognition systems include directly comparing scanned bank notes with stored digital images of bank notes, and also involves color, chemical and paper information. This is computationally intensive resulting in slow processing times. This is unwelcome since short transaction times and large throughput are important to the business of the financial institutions that require these systems.
It is an object of the present invention to provide a system for recognizing different types of sheets in which the above mentioned disadvantage is alleviated.
According to the present invention there is provided a system for recognizing a sheet comprising scanning means for scanning a sheet, storage means for storing a reference relating to a sheet to be recognized, and comparing means for comparing a sheet with said stored reference, characterized by means for producing a diffraction pattern from a sheet, in that the storage means stores at least one matched spatial filter, and in that the comparing means compares said diffraction pattern with the at least one stored matched spatial filter.
Also according to the invention there is provided a recording system for producing matched spatial filters for use in a system for recognizing different types of sheets, characterized by a first scanning means for scanning at least one side of a sheet, a spatial light modulator for providing an optical image of the scanned side of the sheet, light means for passing light through said spatial light modulator, focusing means for producing a diffraction pattern of the image displayed on said spatial light modulator, and a second scanning means for recording a matched spatial filter derived from said diffraction pattern.